The present invention relates in general to semiconductor devices and, more particularly, to high power integrated circuits.
Semiconductor manufacturers often fabricate integrated circuits with protection circuitry in order to increase reliability. For example, an integrated voltage regulator that operates with a high power dissipation and elevated die temperature often includes a thermal shutdown circuit that senses the integrated circuit""s die temperature and turns off the voltage regulator when the die temperature rises to a predefined threshold temperature. When the die cools down, the thermal shutdown circuit turns the voltage regulator back on.
Some thermal shutdown circuits suffer from thermally induced noise caused when they cycle the voltage regulator on and off in rapid succession as the die temperature fluctuates in a small range around a threshold temperature. This cycling produces noise or thermal oscillations which can damage the regulator or external components supplied by the regulator. Many thermal shutdown circuits avoid this problem by incorporating hysteresis that turns off the regulator when the temperature reaches a first predefined level but does not turn the regulator back on until the die temperature falls to a second predefined level which is significantly lower than the first level. However, the built-in hysteresis typically requires a large number of components that occupy a large die area and have a corresponding high fabrication cost.
Hence, there is a need for a thermal shutdown circuit and method that incorporates hysteresis to achieve a high performance while reducing the number of components to provide a low fabrication cost.